1. Technical Field
The present invention relates to an illumination device and a projector.
2. Related Art
Recently, a projector which includes an illumination device provided with a solid light source such as a semiconductor laser, a super luminescent diode (SLD), and a light emitting diode (LED) has been developed or commercialized as a product. The solid light source is small and lightweight, and has considerably high light emission luminance as a result of recent development. Thus, the solid light source is suited for a light source of an illumination device. For example, WO99/49358 discloses a light source of an illumination device which includes a plurality of semiconductor lasers disposed in the form of two-dimensional arrays. This structure allows the illumination device to produce high output.
According to the illumination device having the plural semiconductor lasers, however, the light source is constituted only by a collection of point light sources. In this case, unevenness of illuminance is produced on an illumination receiving area even when uniform illumination on the illumination receiving area is desired. For overcoming this drawback, the illumination device of this type requires an additional optical system for reducing illuminance unevenness of illumination light in some cases. For example, JP-A-2009-42637 discloses a technology of an illumination device having plural laser beam sources, the device reduces illuminance unevenness of illumination light on the illumination receiving area by shifting laser beam entrance areas for entering a fly-eye lens such that intensity patterns of lights stacked on the illumination receiving area can be increased.